HIV-1 SEROCONVERSION RATES AMONG FEMALE COMMERCIAL SEX WORKERS, CHIANG-MAI, THAILAND - A MULTI CROSS-SECTIONAL STUDY

Objectives: To determine HIV seroconversion rates among female commercial sex workers (CSW) in Chiang Mai, Thailand. Design: A three-round multi cross-sectional study was used at approximately 3-month intervals. Methods: In December 1989, 38 brothels (60%) in Chiang Mai were randomly selected. All 518 female CSW in the brothels were interviewed about their sociodemographics, sexual practices, condom use, history of sexually transmitted diseases (STD) and other risk factors. Blood was tested for Venereal Disease Research Laboratory (VDRL)-reactivity and HIV-1 antibody. The same brothels, which were all still operating, were revisited in March and July 1990 and 431 and 320 CSW, respectively, were interviewed and blood-tested. Pelvic examination, cervical, urethral and rectal cultures for gonococcus were added to the study in March 1990, although rectal culture was dropped from the study in July 1990. Results: There were 5.2% [95% confidence interval (Cl), 4.1-10.6] and 3.6% (95% Cl, 1.5-5.4) per woman-month HIV seroconversion rates for the December-March and March-July periods, respectively. Of the CSW, 71.6-77.0% reported histories of at least one STD. Condom-use rates among these CSW were reported to be 85.8-91.8%. High rates of positive cervical (11.2-12.3%) and urethral (8.8-11.4%) cultures for gonococcus were also found in the CSW. Conclusions: The fact that high HIV seroconversion rates and high STD prevalence rates occur despite high rates of reported condom use suggests that more aggressive education programs are needed in Thailand.